1. Field of the Invention
The present invention relates to an ink composition for alcoholic marking pens.
2. Description of the Prior Art
Heretofore, oil based marking pens often called "sign pens" or "felt pens" have been using xylenes, cellosolve or ketones as a main solvent for the ink. Therefore, there are problems such as the undesirable odor and toxicity to man and there is a possibility that methods of using such solvents and environment where such solvents are used may be limited.
These solvents solve the surface of a material on which writing is made with the marking ink, due to their solving property. Therefore, the writing characteristics required for the marker are problematic when the marker is used for writing on widely used materials.
Japanese Patent Application Laid-open No. 128404/1978 discloses an ink composition where a fluorine type surface active agent is added to an oil based ink composition so as to impart water resistance and oil resistance to the written images. However, this ink composition is concerned with an oil based ink which has problems adversely affecting man such as odor, toxicity and the like.
There is not known any ink composition comprising a solvent mainly composed of an alcohol to which the above-mentioned technique is applied.
In order to eliminate those disadvantages, ink compositions comprising ethanol as a substitute for oils have been investigated, but since the resins added for imparting fixability are soluble in ethanol and have affinity to both water and oil and fat to some extent due to the molecular structure of the resins, both water resistance and oil resistance of the ink composition become poor.